1. Field of the Invention
The present invention relates to a signal processing circuit used to determine whether or not the signal level is within a predetermined width and a sensor system using the signal processing circuit.
2. Description of the Related Art
For example, in order to maintain detection accuracy, a sensor system that detects the rotation of an object used in a safety device of a vehicle in a non-contact manner has a function of generating an error signal when a distance (gap) between the sensor system and the object is out of a predetermined range. In such a sensor system, an analog digital converter (ADC) is required in order to detect a reduction (difference) in the sensor output according to the distance.
However, in the case of detecting a gap using the ADC, the circuit size can be reduced by using a sample and hold circuit, but there is a problem that continuous measurement is not possible and accordingly this is not suitable for high-speed processing. In addition, in a circuit that does not use a sample and hold circuit, such as a flash type AD conversion circuit, there is a problem that the circuit size becomes large even though high-speed processing is possible.